The present invention concerns a method to guide a cable burying device effectively as well as accurately along a cable and a device for a cable burying device which buries communication cables or electric cables in the marine bed in order to protect such cables from damages caused by anchors of ships or fishing tools.
In the prior art, when a cable is needed to be buried in the marine bed, the cable is laid and at the same time buried by a burying device which is being tugged by a mother ship. In such a conventional method, the cable is made to be embraced in the burying device on the ship and then the burying device is lowered underwater to the bottom. While the burying device is tugged by the mother ship, an excavation device provided on the burying device excavates a groove on the marine bed and a cable is simultaneously laid and buried in the groove. This method is superior in operability and efficiency for the case to newly lay and bury a cable on the marine floor; however, it has drawbacks when it is applied for such a case that a part of the buried underwater cable is damaged and after such a faulty portion has been repaired aboard the mother ship, the repaired portion is to be re-buried. Since the burying device should be guided along the cable with a high accuracy, a special mother ship with an excellent operational performance is required for such occasions. Further, it is difficult to properly catch and bury the cable because the laid cable tends to take a zigzag course due to tidal currents etc., rather than a straight line. In the prior art, therefore, a considerable length of the cable had to be left unburied. The method has further drawbacks since the burying device is lowered to the bottom floor by ropes after the cable is fed to the device on board of a ship, such ropes tend to be tangled with the cable due to the tidal currents, which not only stops the operation but also damages the cable.